2. Coolant filters have become all the rage, so much so that every diesel shop seems to make their own kit now and there is video after video on YouTube about how people found "casting sand" in their filter when they cut it open. What these people don't realize is that it's NOT casting sand! What that miracle coolant filter has removed from their cooling system is the silicates that have fallen out of suspension because they are not taking care of their coolant. They have filtered out and removed a critical component of the coolant...their cavitation erosion protection is gone and more than likely the are driving around on acidic coolant because they think that "life is good" since they have a filter. Coolant filters were originally developed for the "over the road" trucking industry...and they were NOT designed to be filters in the respect of removing debris. They were originally designed as a way to automatically manage coolant pH (additives). The "filter" was little more than a screen that was full of pellets, and those pellets would dissolve over time and keep the levels of certain additives at the right level, which kept the pH at the right level. When you consider how many miles an OTR truck covers in a year, compared to how many miles your average diesel pickup covers in a year, you can see that some "automated" maintenance for the OTR truck is very important to both engine longevity as well as profitability (less time spend actually working on the truck). Moral of this story...coolant filter DO NOT replace the need to PROPERLY MAINTAIN the coolant! You had better still be testing the coolant and putting in additive!